1) Field of the Invention
The present invention relates to a positioner that positions a head swiftly and precisely on an intended position on a disk, with the aid of an actuator.
2) Description of the Related Art
An external storage device of a computer, which may be a disk device, moves a head to an intended track of a rotating disk to read/write data. This method calls for swift and precise movement of the head on the intended track to improve the speed with which data is accessed.
In the disk device disclosed in Japanese Patent Laid Open Publication No. H9-139032, a feed forward current required for moving the head to the intended position surveys the position to which the head is to be moved, and by correcting the position of the head beforehand so that it coincides with the intended position, the head is moved to the intended position swiftly and precisely.
However, every manufactured magnetic disk device has a VCM (Voice Coil Motor), control system, etc., which have unique characteristics and the conventional technology does not have measures to address the variation in the characteristics. Besides, the characteristics of the VCM vary with aging and temperature as well.
Thus, due to the variation in the characteristics of the VCM, control system etc., with the magnetic disk device, it is not easy to determine beforehand the correction value for the characteristics of voice coil motors and control systems to be used for controlling the magnetic head. If a predetermined correction value is still used, while ignoring the effect of aging or temperature variation on the characteristics of the VCM, there is a danger that the settling of the magnetic head may become unstable.
Thus, the issue is one of addressing the unique characteristics of the VCM and the effect of aging and temperature variation on the characteristics of the VCM, as well as moving the magnetic head swiftly and precisely to the intended position.